THE RECONSTRUCTION AND INTERPRETATIONS OF LAKE STATUS AT 6-KA AND 18-KA BP IN INLAND MAINLAND ASIA

By means of survey of literature through compilations of sedimentologi cal, biogeological and geomorphologic data, the inland take level chan ges in arid or semi-arid mainland Asia at 6 and 18 ka B.P. have been r econstructed. The results showed that the lakes from western and north western Asia were characterized by very high water levels at 18 ka B. P., but low or intermediate water stands at 6 ka B. P. The high lake l evel in this region was associated with the southward displacement of westerlies, therefore, the extent of the high lake stand indicated the southern flank of westerlies during the glaciation. Conversely, the l akes from the eastern and southern Asia registered comparative low lev els at 18 ka B. P, and significantly high one at 6 ka B. P. The toweri ng of lake level at 18 ka B. P. was caused by the weakened summer mons oon and the high lake level at 6 ka B. P. by the enhanced summer monso on induced by the enlarged thermal contrast between land and ocean. Th e extent of high lake levels indicated the northern boundary of monsoo n expansion. Between the above two regions, there is a climatic transi tional zone in the Central Asia where the take behavior was close to t hat in southeastern Asia at 6 ka B. P. but became similar to that in n orthwestern Asia at 18 ka B. P. Thus this zone became a transitional s ector from the monsoon to the westerlies.